1. Field of the Invention
The present invention is concerned with improved seed metering wheel assemblies, which substantially eliminate surges of seed during operation of a seed treater. More particularly, the invention is concerned with such wheel assemblies, and corresponding methods, wherein a rotatable metering wheel assembly is located beneath a seed hopper and has strategically sized and oriented metering openings therethrough. The openings are preferably of different sizes and are arranged in circular arrays so that a substantially constant volumetric and weight output flow of seeds is achieved.
2. Description of the Prior Art
Coating of agricultural seeds is a common practice in sophisticated farming operations. Thus, seeds have been coated with herbicides, fungicides, absorbents, fertilizers, or other chemicals. Generally, specialized seed treaters are used for these purposes and include an inlet hopper, a seed coating device, and a downstream rotatable dryer. A seed metering device is usually provided between the seed hopper and seed coating device, in an effort to give a substantially constant output flow of seeds to the coating device. However, some prior seed metering devices are prone to surging and inconsistent seed flow, which can lead to over- and undercoating of seeds. The problem of seed surging is significant because the usage rate of coating materials normally does not vary once the treater reaches a steady state condition. Accordingly, when a surge occurs, the quantity of seed delivered to the coater is not matched with the supply and application rates of the coating chemicals. Therefore, the seed treater necessarily produces substantial quantities of under-coated seeds.
U.S. Pat. No. 4,465,017 describes a seed coating device having a typical seed metering wheel of spoked design in the form of a circular, axially rotatable wheel having a series of radial spokes extending from a central hub to the rim of the wheel. Metering wheels of the type described in the '017 patent are subject to surging in instances where an unobstructed flow path is presented, which allows a greater rate of seed flow to the downstream coating apparatus.
In order to ameliorate the effects of seed surging, downstream flow-equalizing devices have been employed, which significantly improve the operation of simple seed wheels. However, these accessories add expense and complexity to the metering equipment.
There is accordingly a need in the art for an improved seed metering wheel assembly which is capable of delivering substantially constant flows of seed over a given time period by the essential elimination of undesirable seed surging, without the need for downstream flow equalization devices.